Monday, February 16, 2009

New LRO delay still not official

A leaked internal NASA Email, ahead of any official announcement, has been accepted as Gospel indication that the official launch date of the Lunar Reconnaissance Orbiter (LRO) / Lunar Crater Observation Sensing Satellite (LCROSS) payload combination will slip once again from April 24 to May 7.

NASA's LRO is equipped with, among other instruments, the LROC camera, promising similar HiRISE camera resolution available on its Mars-counterpart the MRO, capable of one to one half-meter resolution deep photography of the lunar surface. While scouting for future safe landing sites for the next steps in returning to the Moon, including locations for the nodes of the International Lunar Network, unambiguous photography of nearly 70 locations of previous human activitiy on the Moon, including and especially the landing sites of Apollo, will be possible ,after decades of "long duration exposure" to the lunar exosphere.

Last year, Japan's Kaguya orbiter returned 5 meter per pixel resolution photography and terrain camera analysis of the landing sites of Apollo 11, 15 and 17, showing a "blast oval" disturbance of the surface brought about by the descent stage of the Apollo 15 Lunar Module Challenger, ferrying astronauts David Scott and Jim Worden into the vicinity of Hadley Rille in 1971. Kaguya spectral camera imagery showing a similar, less obvious "disturbance" resolved high above the landing site of Apollo 11. (From Apollo Command Modules orbiting approximately 100 kilometers overhead as landing missions were underway, handheld and mapping camera photography clearly resolved the Lunar Modules of Apollo 16 and 17.)

At Mars, and at a much high altitude, the MROHiRISE camera "easily" resolved the Mars Rovers Opportunity and Spirit, even resolving their tracks through the martian dust, the Phoenix lander last year and the dusty shells of the thirty year old Viking landers. Indications of dust upon the artifacts of Apollo and other older vehicles on the Moon by LRO would advance understanding of the dynamics of the dusty lunar exosphere and inner solar system space weathering in general.

Riding the same Atlas booster to their eventual polar orbit of the Moon, the LCROSS impactor, a weighted and balanced Centaur upper stage, is destined to be shepherded within 10 kilometers of the interior of one of many possible targets within permanently shadowed polar craters in the high hope of kicking up a sufficient, brief and highly visible plume of material long sheltered from the blast of solar winds, while under the watchful eye of it's Shepherding spacecraft, (for an instant) following it closely behind and LRO in orbit overhead. Institutional observatory teams and thousands of amazingly well-equppeded observers, crossing their fingers for clear skies, will also be watching back on Earth.

Analysis of the debris plume, from the impactor, visible for perhaps 45 seconds, it is hoped, will answer a deeper question posed by consistent data returned first by Clementine (1994) and Lunar Prospector (1999).

NASA has much staked on even a minimal presence of even a very modest permanent, persence of "super" water ice at either lunar pole. Both Clementine and Prospector returned neutron spectography indicating a consistent and strong signature of hydrogen around both lunar poles. Bound with oxygen, hydrogen, of course, becomes water, which is of supreme importance to the survival of life.

Lunar Prospector coincidence-shielded neutron detection showed twice the hydrogen nearest to the moon's north as seemed around the lunar south, and from areas both within and outside of permanently shadowed abyssal craters. Water, if discovered, would most likely be the very long-term sheltering of cometary fragments. That, or the most likely source of sheltered "volatile" elements, like hydrogen, and its compounds might be the equally long-term sheltering of bouncing impacting particles coming to rest in the only two areas of the Moon where they could endure. (Why more hydrogen appears sheltered near the northern polar regions than near the south is a mystery, but the distinct geography of both areas is the likely key.)

Water ice would save a future permanently human presence on the Moon the huge expense of having to ship water out from Earth's far deeper gravity well, or the laborious task of distilling bound oxygen from the lunar surface and combining it with perhaps harder to refine hydrogen.

Such refinements are critical to the receding goal of in situ resource utilization, (ISRU) the Grail of "living off the land" essential to permanent extended human presence on the Moon.

LRO/LCROSS are now soon to be stacked, at the Cape, but late last week KSC schedulers were confronted with logistical problems.

Atlas LRO requires a specific, very ideally a twice monthly, launch window timed so both spacecraft are placed in polar orbit following the terminator's rotation with the Moon, to provide the highest possible relief of surface features available at sunrise and sunset, as the Moon rotates ever-so-slightly eastward under each successive orbit of LRO.

Adding to the need of precision at launch is the timing of an arrival of LCROSS for the best possible view from Earth and from orbit of either the northern field of possible targets or the southern regions, made possible only by the Moon's monthly swing above and below our field of view.

The goals of the LCROSS team require its eventually selected target be as close as possible to this line of sight view from Earth and any change in launch dates leads to busy speculation among the large community of knowledgable and well-equipped observers, particularly concerning LCROSS' eventual target. This most recent rumor of a change a May 7 launch date has swing speculation back to the north.

Veteran lunar observer and LPOD contributor Jim Mosher, writing to the LCROSS Observation news group has said, "the choice of what is a favorable libration also sounds like it may be a difficult call for the mission scientists to make."

"At first blush, it might seem obvious one would want the target area tilted strongly towards Earth, but that creates complications," Mosher wrote, after the initial launch delay last August.

"If the plume is large, its upper parts might have to be observed rising in front of a more distant sunlit (crater) wall - as we have seen would be the case with Faustini, and for the most sensitive instruments there may be a background of Earthshine and ambient light on the dark-appearing crater floor that will have to be subtracted from observations of the lower parts of the plume.

"There might be something to be said for a geometry in which the plume rises purely into the sky above the sunlit foreground crater rim; but that would block from view the lowest and densest parts of the sunlit plume, and would preclude any possibility of seeing (of the) the impact flash - which might be hidden from view by the transient crater, anyway - even if it were nominally in the line of sight). I'm not sure what they will decide."

As of this morning, the Kennedy Space Center Visitor's center launch manifest confirms the rescheduling of the Atlas LRO vehicle for May 7.

Observers on the ground, however, anxiously await an official announcement by NASA.